It is proposed to develop and test the xenon atom as a probe of biological microstructure using nuclear magnetic resonance (NMR) spectroscopy. Systems to be investigated might include simple aqueous systems, micellar solutions, vesicles, multilamellar liposomes, and proteins. The techniques to be used for this investigation include xenon solubility, xenon NMR chemical shift measurements, temperature studies, solvent and paramagnetic ion effects on the Xe chemical shift, 129Xe and 131Xe relaxation time studies, nuclear Overhauser effect measurements, and chemical shift measurements made at high (ca.100 atm) Xe and hydrostatic pressures. The expectation is to show that this small, inert atom is a unique probe capable of reporting structural information on biological microstructures difficult to obtain by other means. In this study information pertinent to the mechanism by which xenon functions as a general anesthetic may be found.